BOULDER, Colorado (AP) -- A 14-year-old girl who claimed she shot her father to death to help him commit suicide has been charged with second-degree murder.

Margaret Rich was charged as a juvenile on Friday, but prosecutor Colette Cribari asked a judge to designate the girl an aggravated juvenile offender, which would limit sentencing options if she is convicted.

A preliminary hearing was set for May 25.

Rich was arrested on March 13, shortly after deputies responded to what they thought was a prank 911 call giving her address. Investigators found the girl's father, Garrett Rich, dead in an upstairs bedroom.

Investigators said the girl was unemotional when they arrived and told them her father had taken his own life. She later acknowledged shooting her father, but only after finding him in pain after he had tried to shoot himself to death.

Authorities did not say at the time whether they believed her story. Sheriff's Lt. Phil West said only that he found it troubling that "by her own admission, she decided to end somebody's life instead of calling for help."

A gag order bars prosecutors, sheriff's deputies, witnesses and others from speaking publicly about the case.

Rich, who has been held without bond, was also charged with first-degree assault.

A Boulder County coroner's report issued this week found that Garrett Rich, whose legal name was Gary Weisser, suffered a gunshot wound to the head and another to the chest.